#include <stdio.h>
#include <ctype.h>
#include "getinput.h"

#define BUFLEN 100 /* size of character buffer */

char buffer[BUFLEN] = "\0";
int nxtbuf = 0; /* next free buffer element */

int getch(void) {

     return (nxtbuf == 0) ? getchar() : buffer[--nxtbuf];
}
	  
int ungetch(int c) {

     if (nxtbuf < BUFLEN) {
	  buffer[nxtbuf++] = c;
	  return 0;
     }

     return -1;
}

/* gets word max length lim and puts in word, skipping comments,
   preprocessor directives, and string literals */
int getword(char *word, int lim) {
     int c;
     char *w = word;

     while ((c = getch()) == ' ' || c == '\t');

     if (c != EOF)
	  *w++ = c;
     if (!isalpha(c)) {
	  *w = '\0';
	  if (c == '#') { /* preprocessor directives */
	       while ((c = getch()) != '\n' && c != EOF)
		    if (c == '/' && (c = getch()) == '*') {
			 ungetch('*');
			 c = '/';
			 break;
		    }
	  }
	  if (c == '/') { /* comments */
	       if ((c = getch()) == '*') {
		    while ((c = getch()) != EOF) {
			 if (c == '*')
			      if ((c = getch()) == '/')
				   return c;
		    }
	       } else {
		    ungetch(c);
		    c = '/';
	       }
	  } 
	  if (c == '\"') /* string constants */
	       while ((c = getch()) != '\"' && c != EOF);
	  return c;
     }
     for ( ; --lim > 0; w++)
	  if (!isalnum(*w = getch()) && *w != '_') {
	       ungetch(*w);
	       break;
	  }
     *w = '\0';
     return word[0];
} /* getword() */

/* puts line, max length len, into s, returning length */
int getline(char *s, int len) {
     char c;
     int i;

     for (i = 0; i < len-1 && (c = getchar()) != EOF && c != '\n'; i++)
	  s[i] = c;
     if (c == '\n')
	  s[i++] = '\n';
     s[i++] = '\0';

     return i;
} /* getline() */